Pathophysiology - Genetics and Disease

The regions of the heterogeneous nuclear RNA that must be spliced out to form functional RNA are called: a. Promoter sites b. Introns c. Exons d. Anticodon

b. Introns Rationale: Introns are spliced from the mRNA before the mRNA leaves the nucleus.

When the nurse is teaching the staff about X-linked recessive disorders, which information should the nurse include? (Select all that apply.) a. The trait is seen much more often in females than in males. b. The trait is never transmitted from father to son. c. The gene can be transmitted through a series of carrier females. d. The gene is passed from an affected father to all his daughters. e. The trait never skips generations.

B, C, D Rationale: The principles of X-linked recessive inheritance include: the trait is seen much more often in males than in females; the trait is never transmitted from father to son; the gene can be transmitted through a series of carrier females; the gene is passed from an affected father to all his daughters, who, as phenotypically normal carriers, transmit it to approximately half their sons, who are affected. X-linked recessive disorders can skip generations since it is a 1 in 4 chance.

An XXY person asks the nurse what this genetic disorder is called. What is the nurse's best response? This disorder is _____ syndrome. a. Turner b. Klinefelter c. Down d. Fragile X

b. Klinefelter Rationale: Individuals with at least two X chromosomes and one Y chromosome in each cell (47 XXY karyotype) have a disorder known as Klinefelter syndrome.

The gradual increase in height among the human population over the past 100 years is an example of: a. A polygenic trait b. A multifactorial trait c. Crossing over d. Recombination

b. A multifactorial trait

A nurse recalls the basic components of DNA are: a. Pentose sugars and four phosphate bases b. A phosphate molecule, deoxyribose, and four nitrogenous bases c. Adenine, guanine, and purine d. Codons, oxygen, and cytosine

b. A phosphate molecule, deoxyribose, and four nitrogenous bases

A couple has three offspring: one child with an autosomal dominant disease trait and two who are normal. The father is affected by the autosomal dominant disease, but the mother does not have the disease gene. What is the recurrence risk of this autosomal dominant disease for their next child? a. 50% b. 33% c. 25% d. Impossible to determine

a. 50% Rationale: For each child with an autosomal dominant disease parent there is a 1 in 2, or 50%, risk.

A 15-year-old female is diagnosed with Prader-Willi syndrome. This condition is an example of: a. Gene imprinting b. An autosomal recessive trait c. An autosomal dominant trait d. A sex-linked trait

a. Gene imprinting

A nurse is reviewing the pedigree chart. When checking for a proband, what is the nurse looking for? a. The person who is first diagnosed with a genetic disease b. The individual who has a disease gene but is phenotypically normal c. The phenotype of genetic material d. The codominance

a. The person who is first diagnosed with a genetic disease Rationale: The pedigree chart summarizes family relationships and shows which members of a family are affected by a genetic disease. The pedigree begins with the proband.

A child is born with blue eyes (bb). The child's mother has blue eyes and the father has brown eyes. Which of the following represents the father? a. Bb b. Bb c. BB d. Bbb

b. Bb

An aide asks the nurse why people who have neurofibromatosis will show varying degrees of the disease. Which genetic principle should the nurse explain to the aide? a. Penetrance b. Expressivity c. Dominance d. Recessiveness

b. Expressivity Rationale: Expressivity is the extent of variation in phenotype associated with a particular genotype. For neurofibromatosis, a variety of manifestations occur among individuals.

After a geneticist talks to the patient about being a chromosomal mosaic, the patient asks the nurse what that means. How should the nurse respond? You may _____ genetic disease(s). a. Only be a carrier of the b. Have a mild form of the c. Have two d. Be sterile as a result of the

b. Have a mild form of the Rationale: A chromosomal mosaic means the body has two or more different cell lines, each of which has a different karyotype; thus, the person has a mild form of the disease.

When homologous chromosomes fail to separate during meiosis, which of the following occurs? a. Neurofibromatosis b. Nondisjunction c. Polyploidy d. Conjoined twins

b. Nondisjunction Rationale: Nondisjunction is an error in which homologous chromosomes or sister chromatids fail to separate normally during meiosis or mitosis.

The condition in which an extra portion of a chromosome is present in each cell is called: a. Reciprocal translocation b. Partial trisomy c. Inversion d. Down syndrome

b. Partial trisomy Rationale: Partial trisomy is a condition in which only an extra portion of a chromosome is present in each cell. A reciprocal translocation occurs when breaks take place in two different chromosomes and the material is exchanged. An inversion occurs when two breaks take place on a chromosome, followed by the reinsertion of the missing fragment at its original site, but in inverted order. Down syndrome is an aneuploidy of the twenty-first chromosome.

To express a polygenic trait: a. Genes must interact with the environment. b. Several genes must act together. c. Multiple mutations must occur in the same family. d. Penetrance must occur.

b. Several genes must act together.

A DNA strand has a region with the sequence ATCGGAT. Which of the following would be a complementary strand? a. CGATACGT b. TAGCCTAG c. TUGCCTUG d. UAGCCUAG

b. TAGCCTAG

The base components of DNA are: a. A, G, C, and U b. P, G, C, and T c. A, G, C, and T d. X, XX, XY, and YY

c. A, G, C, and T

A child is diagnosed with cystic fibrosis. History reveals that the child's parents are siblings. Cystic fibrosis was most likely the result of: a. X inactivation b. Genomic imprinting c. Consanguinity d. Obligate carriers

c. Consanguinity Rationale: Consanguinity refers to the mating of two related individuals, and the offspring of such matings are said to be inbred. Consanguineous matings produce a significant increase in recessive disorders and are seen most often in pedigrees for rare recessive disorders.

A patient has severe mental retardation caused by a deletion of part of chromosome 5. What genetic disorder will the nurse see documented in the chart? a. Prader-Willi syndrome b. Down syndrome c. Cri du chat syndrome d. Trisomy X

c. Cri du chat syndrome Rationale: Cri du chat syndrome means "cry of the cat" and describes the characteristic cry of the affected child. Another symptom of the disorder is mental retardation.

The nurse is teaching staff about the most common cause of Down syndrome. What is the nurse describing? a. Paternal nondisjunction b. Maternal translocations c. Maternal nondisjunction d. Paternal translocations

c. Maternal nondisjunction

Which of the following disorders is manifested primarily in males? a. Cystic fibrosis b. Neurofibromatosis c. Muscular dystrophy d. Klinefelter syndrome

c. Muscular dystrophy

Mutations that do not change the amino acid sequence and thus have no consequence are termed _____ mutations. a. Frameshift b. Spontaneous c. Silent d. Missense

c. Silent

A 20-year-old pregnant female gives birth to a stillborn child. Autopsy reveals that the fetus has 92 chromosomes. What term may be on the autopsy report to describe this condition? a. Biploidy b. Triploidy c. Tetraploidy d. Aneuploidy

c. Tetraploidy Rationale: Tetraploidy is a condition in which euploid cells have 92 chromosomes. Biploidy is a euploid cell with 2 times more chromosomes, or 46. Triploidy is a zygote that has three copies of each chromosome, rather than the usual two. Aneuploidy is when an aneuploid cell does not contain a multiple of 23 chromosomes.

What is the diagnosis of a 13-year-old female who has a karyotype that reveals an absent homologous X chromosome with only a single X chromosome present? Her features include a short stature, widely spaced nipples, reduced carrying angle at the elbow, and sparse body hair. a. Down syndrome b. Cri du chat syndrome c. Turner syndrome d. Klinefelter syndrome

c. Turner syndrome

A 13-year-old girl has a karyotype that reveals an absent homologous X chromosome with only a single X chromosome present. What medical diagnosis will the nurse observe on the chart? a. Down syndrome b. Cri du chat syndrome c. Turner syndrome d. Fragile X syndrome

c. Turner syndrome Rationale: A condition with the presence of a single X chromosome and no homologous X or Y chromosome, so the individual has a total of 45 chromosomes, is known as Turner syndrome. Down syndrome is a change in one arm of a chromosome. Cri du chat syndrome is due to a chromosome deletion. Fragile X syndrome is due to a break or a gap in a chromosome.

A cell that does not contain a multiple of 23 chromosomes is called a _____ cell. a. diploid b. euploid c. polyploid d. haploid

c. polyploid Rationale: A polyploid cell is one in which a euploid cell has more than the diploid number of chromosomes. A diploid cell is when the somatic cell nucleus has 46 chromosomes in 23 pairs. A euploid cell is a cell with multiples of the normal number of chromosomes. A haploid cell has only one member of each chromosome pair, for a total of 23 chromosomes.

When a patient asks what causes cystic fibrosis, how should the nurse respond? Cystic fibrosis is caused by an _____ gene. a. X-linked dominant b. X-linked recessive c. Autosomal dominant d. Autosomal recessive

d. Autosomal recessive

When discussing DNA replication, which enzyme is most important? a. RNA polymerase b. Transfer RNA c. Messenger RNA d. DNA polymerase

d. DNA polymerase Rationale: DNA polymerase is the primary enzyme involved in replication. It adds bases to the new DNA strand and performs "proofreading" functions.

A 50-year-old male was recently diagnosed with Huntington disease. Transmission of this disease is associated with: a. Penetrance b. Recurrence risk c. Expressivity d. Delayed age of onset

d. Delayed age of onset Rationale: A key feature of Huntington disease is its delayed age of onset such that symptoms are not seen until 40 years of age or later.

A 5-year-old male presents with mental retardation and is diagnosed with fragile X syndrome. When the parents ask what caused this, how should the geneticist respond? This was most probably caused from: a. Translocation b. Inversion c. Nondisjunction d. Duplication at fragile sites

d. Duplication at fragile sites Rationale: Unaffected transmitting males have been shown to have more than about 50 repeated DNA sequences near the beginning of the fragile X gene.

Which of the following mutations have the most significant effect on protein synthesis? a. Base pair substitutions b. Silent mutations c. Intron mutations d. Frameshift mutations

d. Frameshift mutations Rationale: The frameshift mutation involves the insertion or deletion of one or more base pairs of the DNA molecule. They alter the amino acid sequence.

A normal male and a female carrier for red-green color blindness mate. Given that red-green color blindness is an X-linked recessive trait, what is the likelihood of their children being affected? a. 25% b. 50% c. Females most affected; no males affected d. Males most affected; no females affected

d. Males most affected; no females affected Rationale: Because a single copy of an X-linked recessive gene will cause disease in a male, whereas two copies are required for disease expression in females, more males are affected by X-linked recessive diseases than are females.

A patient wants to know the risk factors for Down syndrome. What is the nurse's best response? a. Fetal exposure to mutagens in the uterus b. Increased paternal age c. Family history of Down syndrome d. Pregnancy in women over age 35

d. Pregnancy in women over age 35

A patient, age 9, is admitted to a pediatric unit with Duchenne muscular dystrophy. When planning care the nurse recalls the patient inherited this condition through a _____ trait. a. Sex-linked dominant b. Sex-influenced c. Sex-limited d. Sex-linked recessive

d. Sex-linked recessive

A biologist is explaining how RNA directs the synthesis of protein. Which process is the biologist describing? a. Termination b. Transcription c. Translocation d. Translation

d. Translation Rationale: In translation, RNA directs the synthesis of a polypeptide, interacting with transfer RNA (tRNA), a cloverleaf-shaped strand of about 80 nucleotides.

A 12-year-old male is diagnosed with Klinefelter syndrome. His karyotype would reveal which of the following? a. XY b. XX c. XYY d. XXY

d. XXY